The broad, long-term objectives of this proposal are to test, in a subsequent large clinical efficacy trial, if strict control of hyperglycemia in the first 3 days of stroke, with intravenous insulin, will result in better patient outcomes at 3 months than less strict, standard treatment. The specific aims of this Pilot Clinical Trial are: 1) to refine an intravenous insulin protocol that will control hyperglycemia in the first 3 days of stroke better then a standard subcutaneous insulin treatment protocol; 2) to refine the proposed intravenous insulin protocol so that hypoglycemia (glucose<60 mg/dl.) will occur in no more than 20% of subjects; and 3) to collect information essential for an optimized design of a subsequent, large clinical efficacy trial. The essential information to be collected includes comparison of the two insulin treatment protocols for their effect on blood glucose levels, and their safety in the first 3 days of stroke. The health-relatedness of this project is that approximately one third of all acute stroke patients are hyperglycemic, and insulin is well known to effectively treat hyperglycemia. However, an effective and safe intravenous insulin protocol, especially for diabetic patients with acute stroke, has not been reported, and the possible efficacy of such treatment has not been tested. The research design is an initial single-blinded (subjects) acute treatment followed by a final double-blind outcome assessment. Patients with acute ischemic stroke within 12 hours from onset and hyperglycemia (greater than or equal to) 180 mg/dl will be randomized to either standard treatment with subcutaneous insulin or aggressive treatment with intravenous insulin in a 1:2 ratio, respectively. The methods to be used are to treat patients in the standard treatment group with subcutaneous insulin 4 times daily, according to a sliding insulin scale, and patients in the aggressive treatment group with intravenous insulin according to a protocol designed to maintain the blood glucose level 70-130 mg/dl. In both groups, blood glucose will be monitored every 20-120 minutes, depending on the most recent glucose level, and the experimental treatment will continue for 72 hours. Other treatments will be specified and standardized in both groups. Long-term treatment of hyperglycemia will be individualized according to each patient's needs. Additional measurements will include vital signs, serum electrolytes, hemoglobin A-1C, and a global test for multiple clinical outcomes at 3 months.